1. Field of the Invention
The present invention relates to the field of pipe connectors, in particular for high-purity gases, comprising two end-pieces each forming a coupling extremity so as to establish a leak-tight connection between two pipes. The invention is more particularly directed to the different elements which cooperate with the two end-pieces to be coupled together in order to achieve a high standard of leak-tightness between them while providing a simple and compact assembly.
2. Description of the Prior Art
Pipe-connecting devices in most common use up to the present time essentially comprise a male component engaged around an end-piece connected to a first pipe and a female component engaged on an end-piece connected to a second pipe, the two mounted components being intended to cooperate by screwing one onto the other in order to ensure leak-tight locking of the pipes by means of a seal.
Devices of this type with a male component and a female component have the disadvantage of involving torsion of the two end-pieces with respect to each other when they are locked in position by screwing as well as inconvenient assembly since it is necessary to engage the male and female components on the end-pieces in an initial stage. This design concept interferes in particular with the welding of short end-pieces on the pipes. Moreover, the male component which engages within the female component as a result of screwing action entails the need for a bulky connector and this may prove a disadvantage in locations which are not readily accessible. Finally, the mode of assembly is liable to result in a substantial release of particles which disturbs the clean environment often required in installations for the treatment of high-purity gases.
In order to produce connectors which make it possible to overcome the disadvantages mentioned in the foregoing, especially difficulties involved in assembly as well as problems of substantial bulk, it is necessary to permit positive clamping of the seal by accurate axial bearing without any torsional couple as well as to dispense with the need for two different types of end-piece (male and female) and thus to reduce the number of combinations of parts to be employed in order to mount all the connectors of a complete industrial installation.
Consideration may accordingly be given to connectors of the type described in patent No. DE-C-835,090, in which two half-shells located outside the end-pieces clamp these latter against each other without any rotation, the longitudinal locking action of said half-shells being such as to prevent any lateral and longitudinal displacement. This patent also proposes to interpose an intermediate sleeve between the half-shells and the extremities of the end-pieces.
Nevertheless, connectors designed in accordance with the cited patent still remain very imperfect, particularly in regard to precision requirements of installations for the transportation of high-purity gases. Leak-tightness is insufficient if no provision is made for compressing a seal between the end faces of the end-pieces whereas a conventional seal never comes into accurate correspondence with the internal surface of the end-pieces which delimit the axial passageway. Either the seal projects or else it is set back but this in any case produces stagnation zones which are conducive to deposition of dirt.
Furthermore, accurate axial alignment of the internal surfaces of the end-pieces is not possible if the sleeve remains freely mounted within the receiving cavity formed in the half-shells as in the cited patent. And the solution of a sleeve forcibly engaged on the two end-pieces would considerably complicate the assembly and subsequently hinder the clamping action which consists in thrusting the end faces of the end-pieces towards each other in order to ensure leak-tightness.
The present invention provides improvements to this type of connector, in particular by virtue of a special seal so designed as to guarantee an axial passageway without any hollow portion or projecting portion.